Field of the Invention
The present invention relates to an electronic device that accommodates an electronic element in a package, and a method of manufacturing an electronic device.
Background Art
Hitherto, surface-mounted electronic devices have generally been used for mobile phone and mobile information terminals. Meanwhile, in crystal vibrators, micro electro mechanical systems (MEMS), gyroscopes, acceleration sensors, and the like, a hollow cavity is formed inside a package, and an electronic element such as a crystal vibrator and a MEMS is enclosed in the cavity. A glass material is used as the package. For example, the electronic element is mounted on a base substrate, and a glass lid is bonded thereto by anodic bonding, thereby sealing the electronic element. Anodic bonding between glass materials has the advantages of high air tightness and low costs (JP-A-2011-155506).
FIG. 6 is a cross-sectional view of this type of electronic device (FIG. 1 of JP-A-2011-155506). An electronic device 101 includes a base 110, an electronic component 140 mounted on the base 110, and a cap 150 which accommodates the electronic component 140 and is bonded to the base 110. The base 110 is provided with a through electrode 121 passing through the base in a through-thickness direction, a first metal film 122 which is electrically connected to the through electrode 121, and a circuit pattern 130 and a second metal film 123 which electrically connect the through electrode 121 and the electronic component 140 to each other. An external electrode 160 formed of a metal film is formed outside the first metal film 122.
Here, a nickel-iron alloy is used as the through electrode 121. Gold formed by an electroless plating method is used as the first metal film 122. In addition, a low melting point glass, not shown in the drawing, is used between the through electrode 121 and base 110 to improve air tightness by thermal welding.